JP6797085B2 - Fuel injection pump - Google Patents

Description

The present invention relates to a fuel injection pump including an electromagnetic spill valve composed of a solenoid and an armature.

A fuel injection pump that pumps fuel with a plunger has been known for a long time, and a configuration in which the fuel injection amount, fuel injection timing, etc. are controlled by the operation of an electromagnetic spill valve is known (for example, Patent Document 1, Patent Document 1, See 2.).

As understood by referring to FIG. 7A shown as a prior art, in the solenoid spill valve 500 applied to the fuel injection pump, the spill valve body 510 and the spill valve body 510 are slidably inserted. An armature 530 made of a solenoid valve body 520 and a magnetic material fixed to one end of a spill valve body 510 by a fixing bolt 513, and an armature 530 arranged on one side of the solenoid valve body 520 to generate an electromagnetic force that attracts the armature 530. It is provided with a solenoid 540 for sliding the spill valve body 510, and an armature chamber 550 for accommodating an armature 530 provided between the solenoid 540 and the solenoid valve main body 520. The spill valve body 510 is urged by the spill valve spring 511 on the side opposite to the solenoid 540. The armature chamber 550 is communicated with the hollow portion 512 of the spill valve body 510 and the space of the spill valve spring 511, and fuel can flow through the communication hole 531 arranged in the armature 530 and the outer peripheral portion of the armature 530. It is configured in.

Then, in the electromagnetic spill valve 500, when a magnetic force is generated in the solenoid 540 and the armature 530 is attracted to the solenoid 540, the spill valve body 510 slides toward the solenoid 540 against the urging force of the spill valve spring 511. Move. As a result, the electromagnetic spill valve 500 is closed and fuel injection is started. On the other hand, when the magnetic force is not generated in the solenoid 540 and the armature 530 is not attracted to the solenoid 540, the spill valve body 510 slides on the opposite side to the solenoid 540 by the urging force of the spill valve spring 511. As a result, the electromagnetic spill valve 500 opens, and fuel injection ends. In the electromagnetic spill valve 500, the gap between the armature 530 and the end face of the solenoid 540 in the state where the magnetic force is generated in the solenoid 540 and the armature 530 is attracted causes the magnetic force of the solenoid 540 to act more strongly on the armature 530. It is set narrowly.

Further explaining with reference to FIG. 7A, the solenoid 540 constituting the electromagnetic spill valve 500 includes a solenoid core 541 made of a magnetic material, a solenoid coil 543 wound around a recess 542 of the solenoid core 541, and the like. The solenoid case 544 is filled with a mold 560 made of an insulating resin (for example, an insulating polymer) in the case recess 545 of the solenoid case 544, and the solenoid core 541 is embedded and held. Since the space formed by the solenoid core 541 and the solenoid case 544 communicates with the recess 542 of the solenoid core 541, the recess 542 is also filled with the mold 560 by filling the space with the mold 560. .. Therefore, the solenoid coil 543 positioned at a position facing the armature 530 is covered with the mold 560 filled in the recess 542, and the surface 560A of the mold 560 filled in the recess 542 and the end surface 541A of the solenoid core 541 are flush with each other. It is composed.

Japanese Unexamined Patent Publication No. 06-22243 Japanese Unexamined Patent Publication No. 2012-197698

By the way, in a large diesel engine used for ships and the like, low-quality oil such as C heavy oil, which has a higher viscosity than A heavy oil, is generally used as a fuel, but the viscosity is too high at room temperature. Before the fuel is pumped by the fuel injection pump, it is preheated by a heater to reduce its viscosity and supplied to the fuel injection pump, and is also supplied from the fuel injection pump to the combustion chamber of the engine. In this way, if the fuel is preheated and then supplied to the fuel injection pump, the inside of the electromagnetic spill valve is exposed to a high temperature. As described above, the gap between the armature 530 and the solenoid 540 is preferably set to the narrowest possible size so that the magnetic force of the solenoid 540 acts more strongly on the armature 530. However, when the temperature inside the electromagnetic spill valve 500, particularly the armature chamber 550, becomes high and the mold 560 filled in the recess 542 rises above the end face 542 of the solenoid core 540, the spill valve body 510 becomes a seat portion. There is a problem that the desired fuel injection amount is not accurately injected due to a sheet defect that does not come into contact with the fuel. Therefore, in order to prevent seat defects, it is necessary to set a wide gap between the armature 530 and the solenoid 540 when the electromagnetic spill valve 500 is closed. In that case, the magnetic force of the solenoid 540 is difficult to reach the armature 530. Therefore, there arises a problem that the magnetic force of the solenoid 540 must be set to a larger value.

Further, as described above, the electromagnetic spill valve 500 is opened by generating a magnetic force in the solenoid 540 to close the valve and preventing the magnetic force from being generated. At this time, since the armature 530 operates at high speed in the armature chamber 550, when the armature 530 moves in the direction away from the solenoid 540, the pressure in the narrow space between the armature 530 and the solenoid 540 drops sharply. Cavitation occurs. By repeating the generation and disappearance of this cavitation, there is a problem that cavitation erosion occurs in the space composed of the armature 530 and the solenoid 540, and the mold 560 covering the solenoid coil 543 is damaged. This problem becomes more remarkable as the gap between the armature 530 and the solenoid 540 when the electromagnetic spill valve 500 is closed is smaller, that is, the space volume formed by the gap is narrower. In order to deal with this problem, as shown in FIG. 7B, a communication hole 531 is provided in the armature 530 to promote the flow of fuel in the armature chamber 530, or a part of the surface of the mold 560 is lightened. Attempts have been made to suppress the occurrence of cavitation erosion by forming a recess 561, but this measure alone has not been sufficient.

The present invention has been made in view of the above facts, and its main technical problem is a fuel injection pump capable of suppressing the occurrence of cavitation erosion without causing a seat failure in the solenoid spill valve of the fuel injection pump. , And a method of manufacturing a solenoid for a fuel injection pump.

In order to solve the above-mentioned main technical problem, according to the present invention, a fuel injection pump provided with a solenoid spill valve, an armature disposed at one end of a spill valve body constituting the solenoid spill valve, and the armature. It includes at least a solenoid that generates a magnetic force that attracts the armature to operate the spill valve body, and the solenoid is configured by winding a solenoid coil around a recess of the solenoid core to cover the solenoid coil facing the armature. The surface of the mold formed in the recess is formed lower than the height of the surface of the solenoid core , and one end of the spill valve body and the armature are attached to one end of the spill valve body. On the other hand, the central portion of the armature is connected by screwing the fixing bolt, and the fixing bolt includes a region on the solenoid side facing the armature and a hollow portion of the spill valve body. A fuel injection pump provided with a through hole for communicating with, is provided .

Further, in order to solve the above-mentioned main technical problem, according to the present invention, a fuel injection pump provided with a solenoid spill valve and an armature disposed at one end of a spill valve body constituting the solenoid spill valve. The solenoid coil includes, at least, a solenoid that generates a magnetic force that attracts the armature to operate the spill valve body, and the solenoid coil is configured by winding a solenoid coil around a recess of the solenoid core, and the solenoid coil facing the armature. The surface of the mold formed in the recess so as to cover the solenoid core is formed low with respect to the height of the surface of the solenoid core, and one end of the spill valve body and the armature are one with respect to the other. The spill valve body and the armature are connected by being directly screwed together, and the spill valve body and the armature are provided with through holes for communicating the solenoid-side region facing the armature and the hollow portion of the spill valve body . A fuel injection pump is provided.

Further, according to the present invention, there is a method for manufacturing a solenoid constituting an electromagnetic spill valve of a fuel injection pump provided by the present invention, wherein a solenoid is wound around a recess of a solenoid core with respect to a recess of the case of a solenoid case. The burying step of burying the solenoid core together with the coil by a mold made of an insulating resin, and the mold filled in the recess of the solenoid core by the burying step are placed at a predetermined depth from the opening end of the recess of the solenoid core. Provided is a method for manufacturing a solenoid, which includes at least a step forming step of forming a step so that the surface of the mold is lowered with respect to the height of the surface of the solenoid core.

The fuel injection pump configured based on the present invention includes an armature disposed at one end of a spill valve body constituting an electromagnetic spill valve, and a solenoid that generates a magnetic force that attracts the armature to operate the spill valve body. The solenoid is configured by winding a solenoid coil around a recess of the solenoid core, and the surface of the mold formed in the recess so as to cover the solenoid coil facing the armature is the solenoid core. It is formed low with respect to the height of the surface of the spill valve body, and the one end portion of the spill valve body and the armacher are the central portion of the armacher by screwing a fixing bolt to one end portion of the spill valve body. The fixing bolt is provided with a through hole for communicating the solenoid-side region facing the armature and the hollow portion of the spill valve body , or the fixing bolt is provided with a through hole. One end of the spill valve body and the armacher are connected by being screwed directly to the other, and the spill valve body and the armature have a solenoid-side region facing the armature. By providing a through hole for communicating with the hollow portion of the spill valve body, even if the fuel preheated by the heater is supplied to the solenoid spill valve, it is desired without causing a seat failure of the solenoid spill valve. The fuel injection amount can be supplied to the combustion chamber of the engine, and the space volume formed between the armature and the solenoid can be further secured, so that the occurrence of cavitation can be suppressed. Become.

Further, according to the method for manufacturing a solenoid of a fuel injection pump configured based on the present invention, the solenoid core is insulated from the case recess of the solenoid case together with the solenoid coil wound around the recess of the solenoid core. The solenoid core is embedded by a mold made of resin, and the mold filled in the recess of the solenoid core by the burying step is removed from the opening end of the recess of the solenoid core by a predetermined depth. Since a method for manufacturing a solenoid including at least a step forming step of forming a step so that the surface of the mold is lowered with respect to the height of the surface of the solenoid is provided, the fuel preheated by the heater is an electromagnetic spill valve. It is possible to easily manufacture a solenoid that does not cause a seat failure of the electromagnetic spill valve even if it is supplied to.

It is schematic cross-sectional view of the fuel injection pump which concerns on embodiment configured based on this invention. FIG. 1 is a schematic cross-sectional view of (a) an electromagnetic spill valve, an isobaric valve portion, and a solenoid of the fuel injection pump shown in FIG. 1, and (b) a perspective view showing the appearance of the solenoid. (A) Partial cross-sectional view of the fuel injection pump showing the flow of fuel when the electromagnetic spill valve is closed, (b) Partial cross-sectional view of the fuel injection pump showing the flow of fuel when the electromagnetic spill valve is opened. It is a figure. FIG. 5 is a cross-sectional view for expanding and explaining the fuel flow in the vicinity of the armature and the solenoid with respect to the fuel flow when the electromagnetic spill valve shown in FIG. 3 is opened. It is sectional drawing explaining the spill valve body of the fuel-injection pump shown in FIGS. 1 and 2 and another embodiment concerning an armature. It is a conceptual diagram for demonstrating the manufacturing method for manufacturing the solenoid shown in FIGS. 1 and 2. It is a partial sectional view for demonstrating the fuel injection pump in the prior art.

Hereinafter, the fuel injection pump configured based on the present invention will be described in detail with reference to the accompanying drawings.

First, the overall configuration of the fuel injection pump 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In addition, FIG. 1 shows arrows indicating up, down, left and right, and the positions and directions of the respective members described below will be described based on the directions indicated by the arrows.

As shown in FIG. 1, the fuel injection pump 1 includes a pump main body portion 10, an electromagnetic spill valve 20, and an isobaric valve portion 30. The fuel injection pump 1 is used in, for example, a diesel engine (for example, a diesel engine mounted on a ship) in which low-quality oil such as heavy fuel oil C is used as fuel.

The pump main body 10 is provided with a pump main body 11. The barrel hole 111 and the tappet chamber 112 are formed in the pump body 11 so as to extend continuously in the vertical direction. The lower end of the tappet chamber 112 opens on the lower surface of the pump body 11. The tappet 12 is slidably inserted into the tappet chamber 112 in the vertical direction from the lower end opening thereof.

Further, the upper end of the barrel hole 111 is opened on the upper surface of the pump body 11. The plunger barrel 13 is inserted into the barrel hole 111 from the upper end opening thereof. The lower end of the plunger barrel 13 projects into the tappet chamber 112 below the barrel hole 111, while the upper end of the plunger barrel 13 projects upward from the barrel hole 111. A flange portion 131 is formed at the upper end portion of the plunger barrel 13. The plunger barrel 13 is fixed to the upper surface of the pump body 11 via a flange portion 131 with bolts (not shown). Further, an enlarged diameter portion having an enlarged hole diameter is formed in the upper and lower middle portions of the barrel hole 111. The fuel gallery 14 is formed by the enlarged diameter portion and the outer peripheral surface of the plunger barrel 13.

Further, the pump main body 11 is formed with an air bleeding passage 113 connected to the fuel gallery 14, a fuel inlet 114, and a fuel outlet (not shown) arranged side by side on the same plane as the fuel inlet 114. To. The fuel inlet 114 is connected to a feed pump (not shown), and the fuel pumped by the feed pump is fed into the fuel gallery 14 from the fuel inlet 114. Since the outer end of the air bleeding passage 113 is open to the outside of the pump body 11 and the air bleeding bolt 113a that closes the air bleeding passage 113 is detachably attached, the fuel gallery is required for maintenance and the like. The air remaining in the 14 can be evacuated to the outside. Further, the fuel overflowing from the fuel gallery 14 is discharged from the fuel outlet.

Further, the plunger barrel 13 is formed so that the first fuel supply path 132 and the plunger hole 133 extend continuously in the vertical direction. The upper end of the first fuel supply path 132 opens at the upper surface of the plunger barrel 13. Further, the lower end of the plunger hole 133 is opened on the lower surface of the plunger barrel 13. The plunger 15 is slidably inserted into the plunger hole 133 in the vertical direction from the lower end opening thereof. A pressurizing chamber 135 is formed at the upper end of the plunger hole 133 by its inner peripheral surface and the upper end surface of the plunger 15.

Further, the lower end portion of the plunger 15 projects from the plunger hole 133 into the tappet chamber 112 below, and is fixed to the bottom portion in the tappet 12 via the lower spring receiver 16. Further, the upper spring receiver 17 is externally fitted in the plunger barrel 13 projecting downward from the barrel hole 111. A plunger spring 151 is interposed between the upper and lower spring receivers 17 and the lower spring receiver 16. The tappet 12 is urged downward by the plunger spring 151, and the lower surface of the tappet 12 comes into contact with a cam on a cam shaft (not shown) erected below the tappet 12.

Further, the plunger barrel 13 is formed so that the first spill oil discharge path 134 extends upward from the fuel gallery 14 side. The upper end of the first spill oil discharge passage 134 opens at the upper surface of the plunger barrel 13, while the lower end of the first spill oil discharge passage 134 opens in the fuel gallery 14.

Further, the solenoid valve 20 is composed of a solenoid valve main body 21 and a solenoid 23 via a spacer 22 arranged on the right side surface of the solenoid valve main body 21. The solenoid valve main body 21 is fixed to the upper surface of the flange portion 131 of the plunger barrel 13 with a bolt (not shown). The solenoid valve main body 21 is formed so that the discharge valve chamber 211, the isobaric valve spring chamber 212, and the second fuel supply path 213 extend continuously in the vertical direction. The upper end of the discharge valve chamber 211 opens at the upper surface of the solenoid valve main body 21. Further, the lower end of the second fuel supply path 213 is opened on the lower surface of the solenoid valve main body 21.

Further, the solenoid valve main body 21 is formed so that the spill valve hole 214 intersects the second fuel supply path 213 and penetrates the solenoid valve main body 21 in the left-right direction. The spill valve body 24 is slidably inserted into the spill valve hole 214 in the left-right direction.

As can be understood from FIG. 2 (a), which shows the electromagnetic spill valve 20 in a further enlarged state, a spill valve spring chamber 214A is formed at the right end of the spill valve hole 214. The right end of the spill valve spring chamber 214A opens on the right side surface of the solenoid valve body 21. Further, on the left side of the spill valve hole 214, an insert piece chamber 214B is formed at the left end portion thereof, and a communication chamber 214C is formed on the right side of the insert piece chamber 214B. The left end of the insert piece chamber 214B opens on the left side surface of the solenoid valve main body 21. Further, the communication chamber 214C is formed by expanding the diameter of the middle portion of the spill valve hole 214 on the left side in a stepped shape toward the left side via the stepped portion. A valve seat 214D is formed at the stepped portion of the communication chamber 214C. A seal surface 241 to be described later, which is formed on the spill valve body 24, is seated on the valve seat 214D.

Further, the solenoid valve main body 21 is formed so that the second spill oil discharge path 215 extends downward from the communication chamber 214C side. The upper end of the second spill oil discharge passage 215 opens in the communication chamber 214C, while the lower end of the second spill oil discharge passage 215 opens at the lower surface of the solenoid valve main body 21. The second fuel supply path 213 and the second spill oil discharge path 215 are communicated with each other through the spill valve hole 214. The second fuel supply path 213 and the second spill oil discharge path 215 are connected to the first fuel supply path 132 and the first spill oil discharge path 134 of the plunger barrel 13, respectively (see also FIG. 1).

Further, a substantially annular insert piece 25 is inserted into the insert piece chamber 214B from the left end opening thereof, and a stopper 26 is subsequently inserted into the insert piece chamber 214B. The insert piece 25 is fixed in the insert piece chamber 214B by the stopper 26. The spill valve body 24 is slidably inserted into the insert piece 25 in the left-right direction.

Further, the spill valve body 24 is formed so that the hollow portion 242 penetrates the shaft portion of the spill valve body 24 in the left-right direction. The left end of the hollow portion 242 opens in the insert piece 25, while the right end of the hollow portion 242 opens in the armature chamber 221 formed in the spacer 22. Further, a reduced diameter portion 243 is formed on the outer periphery of the axially intermediate portion of the spill valve body 24. The reduced diameter portion 243 is formed by reducing the diameter of the spill valve body 24 in a stepped shape on the outer circumference of the midway portion in the axial direction. A seal surface 241 seated on the valve seat 214D is formed on the left step portion of the step portions on the left and right sides of the reduced diameter portion 243. An armature 247 is provided at the right end of the spill valve body 24. The armature 247 is fixed to the right end opening of the hollow portion 242 of the spill valve body 24 via a fixing bolt 248 to be fastened to the female screw portion 244A formed on the shaft portion of the right end portion of the spill valve body 24, and the armature chamber It is stored in 221. The armature 247 is provided with a communication hole 247A that allows the movement of fuel on the left side and the right side of the armature 247 when the armature 247 moves in the armature chamber 221. The fixing bolt 248 for fixing the armature 247 is formed with a through hole 248A for communicating the hollow portion 242 of the spill valve body 24 and the armature chamber 221 formed based on the present invention.

The armature chamber 221 is formed in a substantially circular shape when viewed from the right side, and both left and right ends thereof are opened on the left and right side surfaces of the spacer 22, respectively. The armature 247 and the solenoid 23 face each other through the right end opening of the armature chamber 221. Further, a spacer-side spring receiver 28 having a protruding hole 281 formed is fitted in the left end opening of the armature chamber 221. The protruding portion 244 of the spill valve body 24 projects from the protruding hole 281 of the spacer-side spring receiver 28.

The protruding portion 244 is formed by reducing the diameter of the right end portion of the spill valve body 24 toward the right in a stepped shape. A gap is formed between the outer peripheral surface of the protruding portion 244 and the inner peripheral surface of the protruding hole 281 to communicate the armature chamber 221 and the spill valve spring chamber 214A. The spill valve body side spring receiver 29 is externally fitted to the stepped portion of the protruding portion 244. A spill valve spring 245 is interposed between the left and right sides of the spill valve body side spring receiver 29 and the spacer side spring receiver 28. The spill valve body 24 is urged to the left (opposite to the solenoid 23) by the spill valve spring 245.

Further, the isobaric valve portion 30 is provided with an isobaric valve holder 31. The isobaric valve holder 31 is fixed to the upper surface of the solenoid valve main body 21 with a bolt (not shown). A discharge valve spring chamber 311 is formed in the lower portion of the isobaric valve holder 31 so as to extend in the vertical direction. The lower end of the discharge valve spring chamber 311 opens at the lower surface of the isobaric valve holder 31. The discharge valve spring chamber 311 is connected to the discharge valve chamber 211 of the solenoid valve main body 21. The discharge valve 32 is housed in the discharge valve chamber 211 and the discharge valve spring chamber 311.

Further, a discharge passage 312 is formed in the vertical portion of the isobaric valve holder 31 so as to extend in the vertical direction. A high-pressure pipe joint (not shown) is attached to the upper part of the isobaric valve holder 31 via the discharge passage 312.

Further, the isobaric valve 33 is housed in the isobaric valve spring chamber 212. The isobaric valve 33 is composed of an isobaric valve body 331, an isobaric valve spring 332, an isobaric valve lower spring receiver 333, and an isobaric valve upper spring receiver 334. The isobaric valve body 331 is urged upward by the isobaric valve spring 332 via the isobaric valve upper spring receiver 334 so as to be seated at the lower end opening of the isobaric valve passage 331B. The lower end of the isobaric valve spring 332 is fixed to the lower surface of the isobaric valve spring chamber 212 via the isobaric valve lower spring receiver 333.

Further, the solenoid 23 includes a solenoid core 231 made of a magnetic material and a solenoid coil 232 wound around the recess 231A of the solenoid core 231, and is a mold made of an insulating polymer with respect to the case recess 233A of the solenoid case 233. It is configured to be held via 234. The solenoid core 231 has an E-shape when viewed from the side (also called an E core), and the solenoid coil 232 is arranged in the space formed by the solenoid core 231 filled with the mold 234 and the solenoid case 233. Since it communicates with the recess 231A, the mold 234 is filled in the case recess 233A, so that the mold 234 is also filled in the recess 231A of the solenoid core 231. Here, in the solenoid 23 configured based on the present invention, the surface 234A of the mold 234 formed in the recess 231A so as to cover the solenoid coil 232 facing the armature 247 is a solenoid core 231 facing the armature 247. It is formed so as to be lower than the height of the surface 231B, and a step is formed between the surface 231B of the solenoid core 231 and the surface 234A of the mold 234. Due to this step, a space portion 231C is formed in the recess 231A of the solenoid core 231. Note that FIG. 2B shows a perspective view of the appearance of the solenoid 23 removed from the electromagnetic spill valve 20 and viewed from the side facing the armature 247. As can be seen from FIG. 2B, the opening of the case recess 233A has a substantially circular shape, and the solenoid core 231 has three surfaces 231B exposed from the filled mold 234 and the solenoid core 231. A space portion 231C is formed in the recess 231A. In FIG. 2B, the space portion 231C is emphasized for convenience of explanation.

The fuel injection pump 1 of the present invention is generally configured as described above, and each operating mode of the fuel injection pump 1 (when the fuel injection pump 1 injects fuel and the fuel injection pump 1 stops fuel injection). This case will be described with reference to FIG. The black arrows in FIG. 3 indicate the fuel flow.

First, when the electromagnetic spill valve 20 constituting the fuel injection pump 1 injects fuel, as shown in FIG. 3A, fuel from a feed pump (not shown) is sent from the fuel inlet 114 to the fuel gallery 14. , The fuel in the fuel gallery 14 is sent to the pressurizing chamber 135. Although not indicated by an arrow, the fuel in the fuel gallery 14 is reduced from the fuel gallery 14 to the first spill oil discharge path 134, the second spill oil discharge path 215, and contraction when the spill valve body 24 is on the left side. It flows in the order of the diameter portion 243, the second fuel supply path 213, and the first fuel supply path 132, and is sent to the pressurizing chamber 135. Then, when the plunger 15 is slid upward according to the rotation of a cam (not shown) and the fuel in the pressurizing chamber 135 is pressurized, this fuel is transferred from the pressurizing chamber 135 to the first fuel supply path 132 and the second. It flows in the order of the fuel supply path 213.

At this time, in the electromagnetic spill valve 20, a magnetic force is generated in the solenoid 23 based on a signal from a control device (not shown), and the armature 247 is attracted to the solenoid 23 as shown in FIG. 3A. Then, the spill valve body 24 is slid to the right (toward the solenoid 23 side) against the urging force of the spill valve spring 245 via the armature 247. Then, the sealing surface 241 of the spill valve body 24 is seated on the valve seat 214D of the spill valve hole 214, and the electromagnetic spill valve 20 is closed. As a result, the communication between the second fuel supply path 213 and the second spill oil discharge path 215 is cut off, so that the fuel pressure in the second fuel supply path 213 is maintained without decreasing. Then, the pressurizing chamber 135, the first fuel supply passage 132, the second fuel supply passage 213, and the isobaric valve spring chamber 212 are in a state of being pressurized with fuel.

Then, in the discharge valve 32, the force for urging the discharge valve body 321 upward (fuel pressure in the isobaric valve spring chamber 212) is the force for urging the discharge valve body 321 downward (attachment of the discharge valve spring 322). When the force becomes larger than the force), the discharge valve body 321 moves upward and separates from the lower surface of the discharge valve chamber 211, and the discharge valve 32 opens. Here, since the isobaric valve 33 is closed, the fuel in the isobaric valve spring chamber 212 does not flow through the isobaric valve passage 331B but passes through the outer periphery of the discharge valve body 321 and is discharged from the discharge valve spring chamber 311. It flows in the order of the passage 313 and is discharged from a high-pressure pipe joint (not shown) connected upward.

On the other hand, when the fuel injection pump 1 ends the injection of fuel, as shown in FIG. 3B, when the electromagnetic spill valve 20 stops generating magnetic force in the solenoid 23 based on the signal from the control device. , The armature 247 is no longer attracted to the solenoid 23. Then, the spill valve body 24 is slid to the left (in the direction opposite to the solenoid 23) until it comes into contact with the stopper 26 by the urging force of the spill valve spring 245. Then, the sealing surface 241 of the spill valve body 24 is separated from the valve seat 214D of the spill valve hole 214, and the electromagnetic spill valve 20 is opened. As a result, the second fuel supply path 213 and the second spill oil discharge path 215 communicate with each other via the spill valve hole 214, so that the fuel pressure in the second fuel supply path 213 decreases. Then, the fuel in the second fuel supply path 213 flows in the order of the spill valve hole 214, the second spill oil discharge path 215, and the first spill oil discharge path 134, is discharged to the fuel gallery 14, and the fuel injection is stopped. Fuel. The fuel in the spill valve hole 214 leaks into the armature chamber 221 from a gap between the inner peripheral surface of the spill valve hole 214 and the outer peripheral surface of the spill valve body 24.

Here, from the state shown in FIG. 3A to the state shown in FIG. 3B, that is, the state in which the magnetic force is generated in the solenoid 23 based on the signal from the control device, the magnetic force is not generated. , The operation of the armature 247 in the armature chamber 221 and the fuel when the armature 247 is no longer attracted to the solenoid 23 and is slid to the left until the spill valve body 24 abuts on the stopper 26 due to the urging force of the spill valve spring 245. The flow will be described with reference to FIG.

As shown in FIG. 4, when the armature 247 is no longer attracted to the solenoid 23 and the spill valve body 24 is slid to the stopper 26 side, that is, to the left by the urging force of the spill valve spring 245, the armature chamber 221 is inside the armature chamber 221. The armature 247 moves at high speed in the direction of the black arrow, and the fuel on the left side of the armature 247 moves to the right side of the armature 247 through the outer periphery of the armature 247 and the communication hole 247A. Further, fuel is supplied to the space composed of the armature 247 and the solenoid 23 from the hollow portion 242 of the spill valve body 24 through the through hole 248A formed in the fixing bolt 248 configured by the present invention. As described above, in the present embodiment, the recess 231A of the solenoid core 231 is configured with the space portion 231C, so that the volume of the space between the armature 237 and the solenoid 23 is secured to be larger. The armature 247 that moves at high speed suppresses the space formed by the armature 247 and the solenoid 23 from becoming negative pressure, and suppresses the occurrence of cavitation.

Further, in the solenoid 23 of the present embodiment, the surface 234A of the mold 234 formed in the recess 231A so as to cover the solenoid coil 232 facing the armature 247 is formed by the surface 231B of the solenoid core 231 and the surface 234A of the mold 234. By forming a step between them, the solenoid core 231 facing the armature 247 is formed so as to be lower than the height of the surface 231B. As a result, when low quality fuel (C heavy oil) or the like is used, the fuel is preheated and supplied in a high temperature state, and even if the mold 234 is raised by heating, it protrudes toward the armature 237 from the surface 231B of the solenoid core 231. Is prevented. Therefore, even if the gap between the armature 247 when it is attracted to the solenoid 23 is made as small as possible, a sheet defect does not occur.

The present invention is not limited to the above-described embodiment, and various modifications can be assumed as long as it belongs to the technical scope of the present invention. Other embodiments of the electromagnetic spill valve 20 will be described with reference to FIG. In the other embodiment shown in FIG. 5, the configurations other than the spill valve body 24'and the armature 247' are the same as those in the above-described embodiment. Therefore, only the differences are described, and other detailed explanations are given. Is omitted.

As shown in FIG. 5, a male screw portion 244'A is formed at the tip end portion of the protruding portion 244'of the spill valve body 24' in another embodiment. Further, a female screw portion 247'B is formed at the center of the armature 247' so that the male screw portion 244'A of the spill valve body 24'is screwed. Further, a through hole 244'B that penetrates to one end is formed in the protruding portion 244', and a through hole 247'C that communicates with the gap formed on the solenoid 23 side is also formed in the central portion of the armature 247'. To. As a result, the region formed by the armature 247'and the solenoid 23 and the hollow portion of the spill valve body 24' are communicated with each other through the through hole 244'B and the through hole 247'C. The through hole 244'B and the through hole 247'C can exert the same effect as the through hole 248A formed in the fixing bolt 248 of the above-described embodiment, and according to the embodiment, the component. It becomes possible to reduce the points.

Further, the present invention is not limited to the other embodiments described above, and for example, a male screw portion is formed on the armature 247'side and a female screw portion is formed on the spill valve body 24'side and directly screwed. (The illustration is omitted).

The manufacturing method of the solenoid 23 applied to the present invention will be described below with reference to FIG.

First, the solenoid case 233 that constitutes the solenoid 23 is formed with a case recess 233A that holds the solenoid core 231. The case recess 233A is filled with a mold 234 made of an insulating polymer to cover the solenoid core 231. The burying step of burying as described above is carried out to obtain the solenoid 23 shown in FIG. 6A. As shown in FIG. 6A, the solenoid coil 232 is wound around the recess 231A of the solenoid core 231, and the solenoid coil 232 is covered by the mold 234 in the recess 231A of the solenoid core 231 to form the solenoid coil 232. The surface of the mold 234 covering the above and the surface 231B of the solenoid core 231 are formed flush with each other.

Next, the mold 234 filled in the recess 231A of the solenoid core 231 is removed from the opening end of the recess 231A of the solenoid core 231 by a predetermined depth with respect to the solenoid 23 subjected to the burying step. A step forming step is performed in which a step is formed so that the surface 234A of the mold 234 filled in the recess 231A is lower than the height of the surface 231B of the solenoid core 231. In the step forming step, for example, as shown in FIG. 6B, the end mill 400 is rotationally driven by a milling apparatus (not shown) to drive the mold 234 to a predetermined depth from the opening end of the recess 231A of the solenoid core 231. Remove only the milling cutter (for example, about 0.5 mm). At this time, the mold 234 is removed without leaving the mold 234 on the inner wall at a predetermined depth from the opening end of the recess 231A (see also FIG. 2B).

By carrying out the above-mentioned burying step and step forming step, a space portion 231C lowered by a predetermined depth from the opening end portion of the recess 231A of the solenoid core 231 is formed, and a space volume for suppressing the occurrence of cavitation. Even if the preheated fuel is supplied and the mold 234 is raised, the solenoid core 231 is prevented from protruding beyond the height of the surface 231B, and the spill valve body 24 is not defective in the seat. The solenoid 23 of the valve 20 is manufactured.

1: Fuel injection pump 10: Pump body 11: Pump body 12: Tappet 13: Plunger barrel 14: Fuel gallery 15: Plunger 20: Solenoid spill valve 21: Solenoid valve body 214: Spill valve hole 214A: Spill valve spring chamber 22 : Spacer 221: Armature chamber 23: Solenoid 231: Solenoid core 231A: Recess 231B: Surface 231C: Space 232: Solenoid coil 233: Solenoid case 233A: Case recess 234: Mold 234A: Surface 237: Armature 24: Spill valve body 242 : Hollow part 244: Protruding part 247: Armature 247A: Communication hole 248: Fixing bolt 248A: Through hole 30: Isobaric valve part

Claims (3)

A fuel injection pump equipped with an electromagnetic spill valve
An armature disposed at one end of a spill valve body constituting the electromagnetic spill valve, and
It includes at least a solenoid that generates a magnetic force that attracts the armature and activates the spill valve body.
The solenoid is configured by winding a solenoid coil around a recess of the solenoid core.
The surface of the mold formed in the recess so as to cover the solenoid coil facing the armature is formed lower than the height of the surface of the solenoid core .
One end of the spill valve body and the armature are connected to the central part of the armature by screwing a fixing bolt to one end of the spill valve body.
A fuel injection pump provided with a through hole for communicating a region on the solenoid side facing the armature and a hollow portion of the spill valve body in the fixing bolt . A fuel injection pump equipped with an electromagnetic spill valve
An armature disposed at one end of a spill valve body constituting the electromagnetic spill valve, and
It includes at least a solenoid that generates a magnetic force that attracts the armature and activates the spill valve body.
The solenoid is configured by winding a solenoid coil around a recess of the solenoid core.
The surface of the mold formed in the recess so as to cover the solenoid coil facing the armature is formed lower than the height of the surface of the solenoid core.
One end portion of the spill valve member, the said armature, which one is engaged Riyui by to be screwed directly to the other,
The The spill valve body and the armature, and the solenoid side of the area facing to the armature, fuel injection pump through hole that provided in communication with the hollow portion, the said spill valve member. The method for manufacturing a solenoid constituting the electromagnetic spill valve of the fuel injection pump according to claim 1 or 2.
A burying step of burying the solenoid core with a mold made of an insulating resin together with a solenoid coil wound around the recess of the solenoid core in the case recess of the solenoid case.
By removing the mold filled in the recess of the solenoid core by the burying step by a predetermined depth from the open end of the recess of the solenoid core, the mold of the mold is made with respect to the height of the surface of the solenoid core. A method for manufacturing a solenoid including at least a step forming step of forming a step so that the surface is low.